Copy paste is the first step to prevent evolution!

Stop copy pasting, not for the sake of introducing bugs but for the sake of preventing your project and yourself from evolving. I keep on stumbling on phrases like:

but that’s how we solved it in that other scenario/class

Ok, then use if for inspiration and try to reuse patterns in the previous solution, but don’t copy and paste the code. At least let your mind attack the problem again with fresh eyes and see how you have evolved from the last time you wrote a solution to a similar problem. I bet that you will come up with never and perhaps cleaner solutions.